class code5 {
    //存在重复元素
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        Map<Integer,Integer> hash = new HashMap<>();
        for(int i=0;i<nums.length;i++) {
            if(hash.containsKey(nums[i])&&i-hash.get(nums[i])<=k) return true;
            hash.put(nums[i],i);
        }
        return false;
    }
}